Gimbal Strut Configuration For High Yaw Suspension Design

ABSTRACT

A trace gimbal is described. The trace gimbal includes outer struts including a front outrigger at a distal end of the trace gimbal and a rear outrigger at a proximal end of the trace gimbal. The front outrigger includes a distal front outrigger and a proximal front outrigger. The rear outrigger includes a distal rear outrigger and a proximal rear outrigger. The trace gimbal also includes a middle strut extending from the distal rear outrigger and adjoining the proximal front outrigger to the rear outrigger. The middle strut extends from a slider tongue adjoining the outer gimbal struts to the slider tongue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.63/094,215 filed on Oct. 20, 2020, which is hereby incorporated byreference in its entirety.

FIELD

This disclosure relates to the field of suspensions for hard diskdrives. More particularly, this disclosure relates to the field ofgimbal struts on an actuated suspension.

BACKGROUND

In a dynamic disk storage device, a rotating disk is employed to storeinformation. Disk storage devices typically include a frame to provideattachment points and orientation for other components, and a spindlemotor mounted to the frame for rotating the disk. A read/write head isformed on a head slider for writing and reading data to and from thedisk surface. The head slider is supported and properly oriented inrelationship to the disk by a suspension that provides both the forceand compliance necessary for proper head slider operation. As the diskin the storage device rotates beneath the head slider and headsuspension, the air above the disk also rotates, thus creating an airbearing which acts with an aerodynamic design of the head slider tocreate a lift force on the head slider. The lift force is counteractedby a spring force of the suspension, thus positioning the head slider ata desired height and alignment above the disk which is referred to asthe fly height.

Suspensions for disk drives include a load beam and a flexure. The loadbeam typically includes a mounting region for mounting the suspension toan actuator of the disk drive, a rigid region, and a spring regionbetween the mounting region and the rigid region. The spring regionprovides a spring force to counteract the aerodynamic lift forcegenerated on the head slider during the drive operation as describedabove. The flexure typically includes a gimbal region having a slidermounting surface where the head slider is mounted. The gimbal region isresiliently moveable with respect to the remainder of the flexure inresponse to the aerodynamic forces generated by the air bearing. Thegimbal region permits the head slider to move in pitch and rolldirections and to follow disk surface fluctuations.

Disk drive manufacturers continue to develop smaller yet higher storagecapacity drives. Storage capacity increases are achieved in part byincreasing the density of the information tracks on the disks (i.e., byusing narrower and/or more closely spaced tracks). As track densityincreases, however, it becomes increasingly difficult for the motor andservo control system to quickly and accurately position the read/writehead over the desired track. Attempts to improve this situation haveincluded the provision of a another or secondary actuator or actuators,such as a piezoelectric, electrostatic or electromagnetic actuator orfine tracking motor, mounted on the head suspension itself. These typesof actuators are also known as dual-stage microactuation devices and maybe located at the base plate, the load beam or on the flexure.

Some of these attempts to improve tracking and head slider positioningcontrol have included locating the actuators both at the base plate andon the flexure tongue simultaneously. Typically, this type of suspensionuses voice coil and the actuator located at the base plate region for alarge motion of the read/write head, while uses the actuator located onthe flexure tongue for a desired fine movement to position theread/write head over the tracks of the disk drive.

SUMMARY

A trace gimbal is described. The trace gimbal includes outer strutsincluding a front outrigger at a distal end of the trace gimbal and arear outrigger at a proximal end of the trace gimbal. The frontoutrigger includes a distal front outrigger and a proximal frontoutrigger. The rear outrigger includes a distal rear outrigger and aproximal rear outrigger. The trace gimbal also includes a middle strutextending from the distal rear outrigger and adjoining the proximalfront outrigger to the rear outrigger. The middle strut extends from aslider tongue adjoining the outer gimbal struts to the slider tongue.

In some examples of the trace gimbal, at least one microactuator ismounted on the slider tongue. The middle strut can support the slidertongue onto which a read/write head is assembled. The proximal frontoutrigger may be adjoined to a distal rear outrigger at a firstjuncture. In some examples of the trace gimbal, the proximal frontoutrigger includes a first cross-section, and a second cross-section atthe first juncture. The second cross-section may be about the samedimension as the first cross-section of the proximal front outrigger.

In some examples of the trace gimbal, the distal rear outrigger includesa cross-section. The middle strut may also include a cross-section,which is about the same dimension as the cross-section of the distalrear outrigger. The middle strut may be adjoined to the slider tongue ata second juncture. In some examples of the trace gimbal, the secondjuncture includes a cross-section at the middle strut, the cross-sectionof the second juncture is about the same dimension as the cross-sectionof the middle strut.

In some examples, the front outrigger, the rear outrigger, and themiddle strut adjoin at a mid-strut joint. The mid-strut joint includes amid-strut length between 0.30 mm and 0.40 mm. The first cross-sectionand the second cross-section of the front outrigger may be between 0.05mm and 0.10 mm.

In some examples of the trace gimbal, the cross-section of the distalrear outrigger is between 0.10 mm and 0.20 mm. The front outrigger andthe rear outrigger may adjoin at a proximal end of the middle strut.

A suspension including a trace gimbal is also described. The suspensionincludes outer struts including a front outrigger at a distal end of thetrace gimbal and a rear outrigger at a proximal end of the trace gimbal.The front outrigger includes a distal front outrigger and a proximalfront outrigger. The rear outrigger includes a distal rear outrigger anda proximal rear outrigger. The suspension also includes a middle strutextending from the distal rear outrigger and adjoining the proximalfront outrigger to the rear outrigger. The middle strut extends from aslider tongue adjoining the outer gimbal struts to the slider tongue.

In some examples of the suspension, at least one microactuator ismounted on the slider tongue. The middle strut can support the slidertongue onto which a read/write head is assembled. The proximal frontoutrigger may be adjoined to a distal rear outrigger at a firstjuncture. In some examples of the suspension, the proximal frontoutrigger includes a first cross-section, and a second cross-section atthe first juncture. The second cross-section may be about the samedimension as the first cross-section of the proximal front outrigger.

In some examples of the suspension, the distal rear outrigger includes across-section. The middle strut may also include a cross-section, whichis about the same dimension as the cross-section of the distal rearoutrigger. The middle strut may be adjoined to the slider tongue at asecond juncture. In some examples of the suspension, the second junctureincludes a cross-section at the middle strut, the cross-section of thesecond juncture is about the same dimension as the cross-section of themiddle strut.

In some examples, the front outrigger, the rear outrigger, and themiddle strut adjoin at a mid-strut joint. The mid-strut joint includes amid-strut length between 0.25 mm and 0.40 mm. The first cross-sectionand the second cross-section of the front outrigger may be between 0.05mm and 0.10 mm.

In some examples of the suspension, the cross-section of the distal rearoutrigger is between 0.10 mm and 0.20 mm. The front outrigger and therear outrigger may adjoin at a proximal end of the middle strut.

While multiple examples are disclosed, still other examples of thepresent disclosure will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative examples of this disclosure. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the disclosure can be obtained, a moreparticular description of the principles described above will berendered by reference to specific examples illustrated in the appendeddrawings. These drawings depict only example aspects of the disclosureand are therefore not to be considered as limiting of its scope. Theprinciples are described and explained with additional specificity anddetail using the following drawings.

FIG. 1 illustrates a top perspective view of a magnetic disk drive unitincluding a microactuator dual stage actuation (DSA) suspension,according to an example of the disclosure.

FIG. 2A illustrates a top plan view of a DSA suspension, according to anexample of the disclosure.

FIG. 2B illustrates a top plan view of a tri-stage actuation (TSA)suspension, according to an example of the disclosure.

FIG. 3 illustrates a gimbal assembly of the trace gimbal of thesuspension of FIG. 2, according to an example.

FIG. 4 illustrates a mid-strut joint of the trace gimbal of FIG. 3,according to an example of this disclosure.

FIG. 5 is a graph of the PZT frequency response function of a suspensionincorporating the mid-strut joint of FIG. 4, according to a simulation.

FIG. 6 illustrates a trace gimbal of a suspension, according to analternative example of the disclosure.

FIG. 7 illustrates a mid-strut joint of the trace gimbal of FIG. 6,according to an example of this disclosure.

FIG. 8 is a graph of the PZT frequency response function of a suspensionincorporating the mid-strut joint of FIG. 6, according to a simulation.

DETAILED DESCRIPTION

FIG. 1 is a top perspective view of a magnetic disk drive unit 100. Thedisk drive unit 100 includes a spinning magnetic disk 101, whichcontains a pattern of magnetic ones and zeroes on it that constitutesthe data stored on the disk drive. The magnetic disk 101 is driven by adrive motor. The disk drive unit 100, according to some examples,includes a suspension 105 with a load beam 107, a base plate 103, and atrace gimbal to which a magnetic head slider is mounted proximate thedistal end of the trace gimbal. The proximal end of a suspension or loadbeam is the end that is supported, i.e., the end nearest to a base plate103 which is swaged or otherwise mounted to an actuator arm. The distalend of a suspension or load beam is the end that is opposite theproximal end, i.e., the distal end is the cantilevered end.

The trace gimbal is coupled to a base plate 103, which in turn iscoupled to a voice coil motor 10. The voice coil motor 10 is configuredto move the suspension arcuately in order to position the head sliderover the correct data track on the magnetic disk 101. The head slider iscarried on a gimbal (not shown), which allows the slider to pitch androll so that it follows the proper data track on the spinning magneticdisk 101, allowing for such variations without degraded performance.Such variations typically include vibrations of the disk, inertialevents such as bumping, and irregularities in the disk's surface.

FIG. 2A is a top plan view of a dual stage actuation suspension 105, inaccordance with an example of the disclosure. The DSA suspension 105 caninclude a base plate 12, and a load beam 107. The load beam 107 includesa trace gimbal 152. The trace gimbal 152 can include mounted actuatorsand a gimbal assembly. The actuators are operable to act directly on thegimbaled assembly of the DSA suspension 105 that is configured toinclude the read/write head slider.

The trace gimbal 152 can include at least one actuator joint 17configured to receive an actuator 14. The base plate 12 illustrates twoactuator joints 17, located on opposing sides of the trace gimbal 152.Each actuator joint 17 includes actuator mounting shelves 18.

Each actuator 14 spans the respective gap in the actuator joint 17. Theactuators 14 are affixed to the slider tongue 18 by an adhesive. Theadhesive can include conductive or non-conductive epoxy strategicallyapplied at each end of the actuators. The positive and negativeelectrical connections can be made from the actuators 14 to the tracegimbal 152 by a variety of techniques. When the actuator 14 isactivated, it expands or contracts producing movements of the read/writehead that is mounted at the distal end of suspension 105 therebychanging the length of the gap between the mounting ends.

The suspension 105 can be configured as a single-stage actuationsuspension, a dual-stage actuation device, a tri-stage actuation deviceor other configurations. One example of the tri-stage actuationsuspension is shown in FIG. 2B, where the actuators 14 and 24 arerespectively located at the mount plate region and on the flexure tongueat the same time. Conceivably, any variation of actuators can beincorporated onto the suspension 105 for the purposes of the examplesdisclosed herein. In other words, the suspension 105 may include more orless components than those shown without departing from the scope of thepresent disclosure. The components shown, however, are sufficient todisclose an illustrative example for practicing the disclosedprinciples.

FIG. 3 illustrates a gimbal assembly of the trace gimbal 152, accordingto an example. The trace gimbal 152 include at least one microactuator150 mounted on a slider tongue 130. The trace gimbal 152 includes outergimbal struts. The outer struts include the front outrigger 110 at adistal end of the trace gimbal 152. The outer struts also include rearoutrigger 140 at a proximal end of the trace gimbal 152. The tracegimbal 152 also includes a middle strut 120 extending from the rearoutrigger 140 and connecting the front outrigger 110 to the rearoutrigger 140. In other words, the front outrigger 110 and the rearoutrigger 140 adjoin at the proximal end of the middle strut 120. Thetrace gimbal 152 also includes an inner strut 160 extending from theslider tongue 130 and connecting the middle strut 120 to the slidertongue 130. The inner strut 160 supports the slider tongue 130 ontowhich a read/write head is assembled.

The front outrigger 110, the rear outrigger 140, the middle strut 120,and the inner strut 160 (collectively referred to as “struts”) areconfigured to bend when an actuation voltage is applied to the topsurface of the microactuator 150, thus actuating the microactuator 150.The struts act as microactuation hinges that flex to allow the distalend of the trace gimbal 152 (and therefore a slider) to movehorizontally when the microactuator 150 is actuated. The struts havehigh lateral stiffness to attain high sway frequency, yet are flexibleenough to allow the distal end of the trace gimbal 152 to be rotatedabout the dimple 170 by operation of microactuator 150. To accomplishthis, according to some examples, the struts have varying crosssectional sizes. For example, the struts are bowed and/or bent as shownfor example in FIG. 3 to provide flexibility for the microactuatoroperation. The middle strut 120 and the inner strut 160 are adjoined ata mid-strut joint.

FIG. 4 illustrates the mid-strut joint 11 of the trace gimbal 152,according to an example. The mid-strut joint 11 includes a proximalfront outrigger 114 adjoined to a distal rear outrigger 142 at a firstjuncture 116. The proximal front outrigger 114 can include a firstcross-section 115, and a second cross-section 117 at the first juncture116. The second cross-section 117 is equal or larger than the firstcross-section 115 of the proximal front outrigger 114. The distal rearoutrigger 142 can include a first cross-section 143, while a proximalrear outrigger 144 has a second cross-section 145 (in FIG. 3), largerthan the first cross-section 143. The middle strut 120 includes across-section 121, which is also smaller than the second cross-section145 (in FIG. 3) of the proximal rear outrigger 144.

The middle strut 120 is adjoined to the inner strut 160 at a secondjuncture 170. The second juncture 170 includes a first cross-section 171at the middle strut 120. The second juncture 170 also includes a secondcross-section 173 at the inner strut 160, where the second cross-section173 is larger than the first cross-section 171. The inner strut 160includes a cross-section 161. The inner strut 160 is adjoined to theslider tongue 130 at a third juncture 190. The third juncture 190includes a cross-section 191. The slider tongue 130 includes across-section 131, that is larger than the cross-section 191 of thethird juncture 190, which is larger than the cross-section 161 of theinner strut 160.

The varying cross-sections of the distal rear outrigger 142, theproximal rear outrigger 144, and the proximal front outrigger 114impacts the performance of a suspension device with such a trace gimbal152.

FIG. 5 is a graph 300 of the microactuator (PZT) frequency responsefunction of a suspension incorporating the trace gimbal 152, accordingto a simulation. The suspension exhibited a yaw frequency below 50 kHz.Because the yaw mode gain is the highest peak across the frequency bandof the frequency response function, a deep notch filter is needed to beplaced at the yaw mode for its gain attenuation, which sets the limit ofthe servo bandwidth.

FIG. 6 illustrates a trace gimbal 200 of a suspension, according to anexample of the disclosure. The trace gimbal 200 includes at least onemicroactuator 250 mounted on a slider tongue 230. The trace gimbal 200includes outer gimbal struts. The outer struts include the frontoutrigger 210 at a distal end of the trace gimbal 200, the frontoutrigger 210 includes a distal front outrigger 212 and a proximal frontoutrigger 214. In some examples, the distal front outrigger 212 and theproximal front outrigger 214 are defined by a bend or non-linear featureof the front outrigger 210. In other examples, the distal frontoutrigger 212 and the proximal front outrigger 214 arenon-distinguishable, and may be adjoined at a linear feature that doesnot physically separate the two features.

The outer struts also include rear outrigger 240 at a proximal end ofthe trace gimbal 200, the rear outrigger 240 includes a distal rearoutrigger 242 and a proximal rear outrigger 244. In some examples, thedistal rear outrigger 242 and the proximal rear outrigger 244 aredefined by a bend or non-linear feature of the rear outrigger 240. Inother examples, the distal rear outrigger 242 and the proximal rearoutrigger 244 are non-distinguishable, and may be adjoined at a linearfeature that does not physically separate the two features.

The trace gimbal 200 also includes a middle strut 220 extending from thedistal rear outrigger 242 and adjoining the proximal front outrigger 214to the rear outrigger 240. In other words, the front outrigger 210 andthe rear outrigger 240 adjoin at the proximal end of the middle strut220. The middle strut 220 also extends from the slider tongue 230adjoining the outer gimbal struts to the slider tongue 230. The middlestrut 220 supports the slider tongue 230 onto which a read/write head isassembled. The trace gimbal 200 avoids the bowed and/or bent element ofan inner strut, thereby improving the stiffness of the trace gimbal 200.

FIG. 7 illustrates a mid-strut joint 201 of the trace gimbal 200,according to an example of this disclosure. The mid-strut joint 201includes a proximal front outrigger 214 adjoined to a distal rearoutrigger 242 at a first juncture 216. The proximal front outrigger 214can include a first cross-section 215, and a second cross-section 217 atthe first juncture 216. The second cross-section 217 is about the samedimension as the first cross-section 215 of the proximal front outrigger214. One of ordinary skill in the art understands that two machinedcomponents are rarely the same dimension. Therefore, the dimensionsdiscussed herein with respect to the illustrated examples account formanufacturing tolerances and in practice are not expected to be exact.The distal rear outrigger 242 can include a cross-section 243. Themiddle strut 220 includes a cross-section 261, which is about the samedimension as the cross-section 243 of the distal rear outrigger 242.

The middle strut 220 is adjoined to the slider tongue 230 at a secondjuncture 270. The second juncture 270 includes a cross-section 271 atthe middle strut 220. The cross-section 271 of the second juncture 270is about the same dimension as the cross-section 261 of the middle strut220. The slider tongue 230 includes a mid-strut joint length L 221, thatis greater than the cross-section 271 of the second juncture 270.

Specifically, the mid-strut joint 201 may have a mid-strut length L 221between 0.20 mm and 0.40 mm. In some examples, the mid-strut length L221 is 0.25 mm. The first cross-section 213 and the second cross-section215 of the front outrigger 210 is between 0.05 mm and 0.10 mm. In someexamples, the width of both cross-sections is 0.09 mm. The cross-section243 of the distal rear outrigger 242 is between 0.10 mm and 0.20 mm. Insome examples, the width of the cross-section 243 is 0.12 mm. The middlestrut 220 connects to the slider tongue 230 at a position thatsubstantially increases the mid strut joint length, compared to thetrace gimbal of FIG. 3. In some examples, the mid strut joint length 221is more than two-times the mid strut joint length of the trace gimbal ofFIG. 3.

FIG. 8 is a graph 400 of the microactuator (PZT) frequency responsefunction of a suspension incorporating the mid-strut joint of FIG. 7,according to a simulation. The increased mid strut joint lengthincreases the yaw frequency. For example, a 0.1 mm increase in mid strutjoint length lead to the yaw frequency increase by 8 kHz to 65.0 kHz. Inaddition, the mid strut joint length increase also improves the 24 kHzmode (the torsion mode) as it increases its phase lag to decrease thegain.

While multiple examples are disclosed, still other examples within thescope of the present disclosure will become apparent to those skilled inthe art from the detailed description provided herein, which shows anddescribes illustrative examples. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and notrestrictive. Features and modifications of the various examples arediscussed herein and shown in the drawings. While multiple examples aredisclosed, still other examples of the present disclosure will becomeapparent to those skilled in the art from the following detaileddescription, which shows and describes illustrative examples of thisdisclosure. Accordingly, the drawings and detailed description are to beregarded as illustrative in nature and not restrictive.

What is claimed is:
 1. A trace gimbal comprising: outer struts includinga front outrigger at a distal end of the trace gimbal and a rearoutrigger at a proximal end of the trace gimbal, the front outriggerincludes a distal front outrigger and a proximal front outrigger, therear outrigger includes a distal rear outrigger and a proximal rearoutrigger; and a middle strut extending from the distal rear outriggerand adjoining the proximal front outrigger to the rear outrigger,wherein the middle strut extends from a slider tongue adjoining theouter gimbal struts to the slider tongue.
 2. The trace gimbal of claim1, further comprising at least one microactuator mounted on the slidertongue, wherein the middle strut supports the slider tongue.
 3. Thetrace gimbal of claim 1, wherein the proximal front outrigger isadjoined to a distal rear outrigger at a first juncture.
 4. The tracegimbal of claim 3, wherein the proximal front outrigger includes a firstcross-section, and a second cross-section at the first juncture, whereinthe second cross-section is about a same dimension as the firstcross-section of the proximal front outrigger.
 5. The trace gimbal ofclaim 4, wherein the first cross-section and the second cross-section ofthe front outrigger is between 0.05 mm and 0.10 mm.
 6. The trace gimbalof claim 1, wherein the distal rear outrigger includes a cross-section,wherein the middle strut includes a cross-section, which is about a samedimension as the cross-section of the distal rear outrigger.
 7. Thetrace gimbal of claim 6, wherein the cross-section of the distal rearoutrigger is between 0.10 mm and 0.20 mm.
 8. The trace gimbal of claim1, wherein the middle strut is adjoined to the slider tongue at a secondjuncture, the second juncture includes a cross-section at the middlestrut, the cross-section of the second juncture is about a samedimension as the cross-section of the middle strut.
 9. The trace gimbalof claim 1, wherein the front outrigger, the rear outrigger, and themiddle strut adjoin at a mid-strut joint, the mid-strut joint includes amid-strut length between 0.0.25 mm and 0.40 mm, which is more than twotimes of the cross sections of the front outrigger, the rear outriggerand the middle strut.
 10. The trace gimbal of claim 1, wherein the frontoutrigger and the rear outrigger adjoin at a proximal end of the middlestrut.
 11. A suspension comprising: a trace gimbal including: outerstruts including a front outrigger at a distal end of the trace gimbaland a rear outrigger at a proximal end of the trace gimbal, the frontoutrigger includes a distal front outrigger and a proximal frontoutrigger, the rear outrigger includes a distal rear outrigger and aproximal rear outrigger; and a middle strut extending from the distalrear outrigger and adjoining the proximal front outrigger to the rearoutrigger, wherein the middle strut extends from a slider tongueadjoining the outer gimbal struts to the slider tongue.
 12. Thesuspension of claim 11, further comprising at least one microactuatormounted on the slider tongue, wherein the middle strut supports theslider tongue.
 13. The suspension of claim 11, wherein the proximalfront outrigger is adjoined to a distal rear outrigger at a firstjuncture.
 14. The suspension of claim 13, wherein the proximal frontoutrigger includes a first cross-section, and a second cross-section atthe first juncture, wherein the second cross-section is a same dimensionas the first cross-section of the proximal front outrigger.
 15. Thesuspension of claim 14, wherein the first cross-section and the secondcross-section of the front outrigger is between 0.05 mm and 0.10 mm. 16.The suspension of claim 11, wherein the distal rear outrigger includes across-section, wherein the middle strut includes a cross-section, whichis a same dimension as the cross-section of the distal rear outrigger.17. The suspension of claim 16, wherein the cross-section of the distalrear outrigger is between 0.10 mm and 0.20 mm.
 18. The suspension ofclaim 11, wherein the middle strut is adjoined to the slider tongue at asecond juncture, the second juncture includes a cross-section at themiddle strut, the cross-section of the second juncture is about a samedimension as the cross-section of the middle strut.
 19. The suspensionof claim 11, wherein the front outrigger, the rear outrigger, and themiddle strut adjoin at a mid-strut joint, the mid-strut joint includes amid-strut length between 0.25 mm and 0.40 mm.
 20. The suspension ofclaim 11, wherein the front outrigger and the rear outrigger adjoin at aproximal end of the middle strut.